A silicon wafer manufacturing process is generally performed by growing a silicon monocrystal by a Czochralski (CZ) method. The Czochralski method is a method of growing the silicon monocrystal by charging a polysilicon into a quartz crucible and subjecting to a high temperature to form a silicon melt solution, and then contacting a silicon seed to the silicon melt solution and slowly rotating.
A silicon ingot is formed by pulling the silicon seed up, and a silicon wafer is manufactured by processes such as a slicing for cutting such a ingot perpendicular to a crystal growing direction, a lapping for mitigating applied damage during the slicing, a polishing to make a rough wafer surface to have a high level of flatness, and the like.
Since a silicon wafer is manufactured by slicing a silicon ingot, the quality of the silicon ingot may directly indicate the quality of the silicon wafer. Accordingly, there has been proposed various methods for improving the quality of a silicon ingot such as a method of controlling the diameter of the ingot to be constant during growth of the ingot.
As one example, a monocrystal growing apparatus for controlling the diameter of a silicon ingot to be constant includes a sensor part sensing characteristics of a meniscus which is a contact surface between the silicon melt solution of the quartz crucible and the growing ingot, and a diameter deriving part for deriving the diameter of the ingot through the characteristics of the meniscus detected by the sensor part. And a driver connected to the sensor part to change a sensing area of the sensor part, and a control part controlling the diameter of the ingot to increase or decrease based on the diameter of the ingot derived through the diameter deriving part. Accordingly, it is possible to accurately control the diameter of the ingot by calculating the diameter of the actual ingot by changing the sensing area of the sensor or correcting the derived diameter.
As described above, a method for improving the quality of the ingot has been proposed, but there is no method for confirming a growth interface shape of the ingot during growth of the ingot.
FIG. 1 is a view illustrating various interface shapes of a growing ingot.
Referring to FIG. 1, an interface of the ingot may be grown in a concave shape like (a) and (b) on the basis of a growth direction, flat shape like (c), or convex shape like (d). Conventionally, such an interface of the ingot may not be confirmed during a growing process of the ingot, but after growth of the ingot is completed, the quality of the ingot is checked and it may be confirmed whether the interface of the ingot is convex or concave.
In fact, the shape of the ingot interface during growth of the monocrystal has a great influence on the final quality of the ingot, and if the change in the growing interface may be determined in real time, the quality of RRG or ORG may be improved and the growth rate of the monocrystal may also be increased by controlling a balance of heat that escapes to the ingot. Therefore, in growing of the monocrystal, a method of determining the change of the interface during growth of the ingot is required.